Connecting part for connecting a fuel line to a fuel injection valve

ABSTRACT

A connecting element for connecting a fuel line to a fuel injector has a first connecting sleeve ( 2 ), which may be inserted into a receiver opening in the fuel line, and a first sealing element ( 7 ) positioned on the first connecting sleeve ( 2 ). The connecting element ( 1 ) has a second connecting sleeve ( 3 ), on the end diametrically opposed to the first connecting sleeve ( 2 ), which may be inserted into a recess in the fuel injector and on which a second sealing element ( 8 ) is positioned. A radially expanded region ( 4 ) is formed between the first and second connecting sleeves ( 2, 3 ), whose transition to at least one of the two connecting sleeves ( 2, 3 ) is formed as a first contact surface ( 5, 6 ), which, when the connecting element ( 1 ) is mounted, is in contact with a corresponding surface on one of the adjoining components.

Background Information

[0001] The present invention is directed to a connecting element according to the definition of the species in the main claim.

[0002] For connecting a fuel injector to a fuel line, due to the installation situation, a connecting element is necessary in many cases between the fuel injector and the fuel supply line for compensating the position tolerance. This is true in particular in direct-injection internal combustion engines, which supply multiple fuel injectors with fuel via a shared fuel line, the fuel rail.

[0003] A fuel injection system having one adapter per injector is known from German Patent Application 197 35 665 A1. The adapter described there has two different connections. On one side, the adapter has a connecting sleeve which may be inserted into an opening of the fuel line. On the opposite end, a receiver opening is introduced into the adapter, into which the connection side of the fuel injector may be inserted. In this case, the receiver opening has, in particular, an internal geometry which is identical to the opening in the fuel line. The adapter thus acts like an extension of the fuel injector or of the connecting sleeve of the fuel line. A peripheral shoulder is made on the outside of the adapter, via which the adapter may be connected to the fuel line by a holding clamp and secured against slipping out.

[0004] The adapter is sealed by two sealing elements, which are typically formed as O-rings. The first sealing element, which is used to seal the adapter in relation to the fuel line, is positioned in a groove on the connecting sleeve of the adapter in this case. In contrast, the seal between the fuel injector and the adapter is produced by a second sealing element positioned on the fuel injector.

[0005] The necessity of fixing the adapter on the fuel rail using a holding clamp is disadvantageous in the adapter described. This requires not only an additional work step during the assembly of the internal combustion engine, but also additional expenditure for parts. In addition, it is disadvantageous that the spacer must be inserted with a certain orientation during assembly.

[0006] Furthermore, the limited elasticity of the holding clamp results in the adapter having force applied to it unequally in the event of tilting of the adapter in relation to the fuel line, so that pinching of the sealing element and, finally, failure of the sealing element may occur.

[0007] It is also disadvantageous that an additional clamping shoe is necessary in order to fix the fuel injector in the cylinder head of the internal combustion engine. The adapter is unable to transmit axial forces and, due to its restricted movability, is only able to compensate position tolerances to a limited degree. In particular in long fuel rails, temperature variations which may occur during operation of an internal combustion engine result in relatively large changes in length of the fuel line and therefore, in particular in long fuel rails, to changes in length of the connecting sleeves which cannot be compensated for.

ADVANTAGES OF THE INVENTION

[0008] In contrast to the related art, the connecting element according to the present invention having the characterizing features of the main claim has the advantage that, due to the design of the connecting element having two diametrically opposed connecting sleeves and the contact surfaces formed between them, a separate holding clamp may be dispensed with. The connecting element is fixed in its position between the fuel injector and the fuel line by the contact surfaces. Position tolerances or changes in length of the fuel line due to temperature variations do not result in forces being introduced asymmetrically into the sealing elements, because of the lack of additional fixing.

[0009] Advantageous refinements of the connecting element according to the present invention are possible using the features described in the subclaims.

[0010] The design of at least one of the two surfaces as a section of a spherical surface allows rotation of the connecting element around a defined center of rotation. If both contact surfaces are designed in spherical geometry and the centers of the spherical geometries lie in the plane of the sealing elements, the uniform load of the sealing elements in the event of tilting of the connecting element resulting therefrom is advantageous in particular. This is of significance above all for repeated loading which arises due to temperature expansion of the rail, since premature wear of the sealing elements is prevented.

[0011] The possibility of transmitting a force which presses the fuel injector against the cylinder head using the connecting element on the fuel injector is especially advantageous. In this way, the fuel injector is held securely in the cylinder head without further mounting elements. The clamping shoes typically used may be dispensed with, through which, in addition to the material costs, further processing steps may be saved, e.g., cutting threads in the cylinder head for screwing in the clamping shoe.

[0012] Forming different faces on the side of the fuel line and the side of the fuel injector allows the force resulting therefrom to be used to elevate the pressure on the fuel injector.

[0013] If a connecting element is used in which both connecting sleeves have an identical geometry, especially simple mounting is possible. The connecting element may be mounted in any desired way. The orientation of the component as an additional work step before insertion may thus be dispensed with.

DRAWING

[0014] An exemplary embodiment of a connecting element according to the present invention is illustrated in simplified form in the drawing and is explained in more detail in the following description.

[0015]FIG. 1 shows a schematic partial section through an exemplary embodiment of a connecting element according to the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0016] A schematic illustration of a connecting element 1 according to the present invention for connecting a fuel injector (not shown) to a fuel line (not shown) is shown in FIG. 1. Connecting element 1 according to the present invention essentially includes three sections. A first connecting sleeve 2, a radially expanded region 4, and a second connecting sleeve 3 are positioned sequentially in the axial direction.

[0017] First connecting sleeve 2 has a reduction of its radial dimension in the direction of the end of connecting element 1 and thus forms a first shoulder 11. A first supporting disk 9, whose internal radial dimension is smaller than the radial dimension of first connecting sleeve 2 on the side of expanded region 4, is positioned on first shoulder 11. In contrast, the external radial dimension of first supporting disk 9 is larger than the maximum radial dimension of first connecting sleeve 2. The outer end of first connecting sleeve 2 is formed as a first collar 13, whose external radial dimension preferably corresponds to the external radial dimension of first supporting disk 9. The radial dimensions of first collar 13 and first supporting disk 9 are sufficiently smaller than the internal radial dimension of the receiver opening of the adjoining component (e.g., of the receiving connecting sleeve of the fuel line), that connecting element 1 may be slanted by a specific angle in relation to the receiving component without first supporting disk 9 or first collar 13 hitting the inner wall of the adjoining component.

[0018] First collar 13 and first supporting disk 9 are separated in the axial direction. A first sealing element 7 is positioned in the resulting gap. An O-ring may be used, for example, as first sealing element 7, as shown in FIG. 1. The height and radial dimension of the gap formed between first supporting disk 9 and first collar 13 are dimensioned to correspond to the nominal size of the O-ring to be used.

[0019] The design of the opposite end of connecting element 1 corresponds to the preceding description. A second sealing element 8 is positioned between a second collar 14, which is positioned on the end of connecting element 1, and a second supporting disk 10, which rests on a second collar 12. The external radial dimensions are again dimensioned so that second connecting sleeve 3 may be tilted in the receiver opening of the adjoining component (e.g., of the fuel injector) by a specific angle, without second supporting disk 10 or second collar 14 striking against the inner wall of the receiver opening. The geometries of first and second connecting sleeves 2 and 3 are preferably identical, so that a symmetrical connecting element 1 results, whose orientation does not have to be established during installation.

[0020] For mounting of supporting disks 9 and 10, connecting element 1 may, for example, have multiple parts. For example, first and second collar 13 and 14 may be designed as individual components together with the part of first or second connecting sleeve 2 or 3 which is reduced in the radial dimension and, after placement of supporting disks 9 and 10, may be pressed into the middle part of connecting element 1.

[0021] Supporting disks 9, 10 are, for example, slotted and have an external diameter which is larger than the opening of the adjoining component. Due to the slotted design, supporting disks 9, 10 always press against the outer diameter of the hole of the adjoining component. With a proper layout of supporting disks 9, 10, a gap to connecting sleeves 2, 3 of connecting element 1 always remains at the internal diameter.

[0022] A first contact surface 5, whose geometry corresponds to a section of a spherical surface, is formed as a transition from first connecting sleeve 2 to expanded region 4. The center of this spherical geometry having first radius R1 is, for example, identical to the intersection of central axis 18 of connecting element 1 and central plane 19 of second sealing element 8. The transition from second connecting sleeve 3 to expanded region 4 is also formed as a section of a spherical surface, its center, for example, being identical to the intersection of central axis 18 of connecting element 1 with central plane 20 of first sealing element 7, and the spherical surface having a second radius R2.

[0023] When connecting element 1 has been installed, the two contact surfaces 5 and 6 are each supported on a corresponding surface on the fuel line and the fuel injector. A force may thus be exerted by the fuel line on the fuel injector in the axial direction. The fuel injector is thus fixed in the cylinder head by connecting element 1. The forces necessary to keep the fuel injector fixed in the cylinder head are absorbed, on the side diametrically opposed to the fuel injector, by the fuel line, which is attached to the internal combustion engine. In the event of position tolerances, which may arise during manufacture, connecting element 1 may slant between the fuel line and the fuel injector. In this case, connecting element 1 rotates around both centers of spherical contact surfaces 5 and 6. Furthermore, the spherical geometry of both contact surfaces 5 and 6 ensures a uniform supporting surface in this case. The radii of both contact surfaces 5 and 6 are selected in accordance with the corresponding surfaces on the fuel line and the fuel injector.

[0024] A first and a second face 15 and 16 are formed on the two ends of connecting element 1. Both faces 15 and 16 may have different sizes. If both differently sized faces 15 and 16 have the fuel pressure applied to them, a resulting force arises on connecting element 1 in the direction of smaller face 15 or 16. This resulting force may be used to increase the force with which the fuel injector is held in the cylinder head. Connecting element 1 has an inner through hole 17 in order to ensure the fuel flow from the fuel distributor to the fuel injector. 

What is claimed is:
 1. A connecting element for connecting a fuel line to a fuel injector, having a first connecting sleeve (2), which may be inserted into a receiver opening in the fuel line, and a first sealing element (7) positioned on the first connecting sleeve (2), wherein, on the end diametrically opposed to the first connecting sleeve (2), the connecting element (1) has a second connecting sleeve (3) which may be inserted into a recess in the fuel injector and on which a second sealing element (8) is positioned, and a radially expanded region (4) is formed between the first and second connecting sleeves (2, 3), whose transition to at least one of the two connecting sleeves (2, 3) is designed as a first contact surface (5, 6), which, when the connecting element (1) is mounted, is in contact with a corresponding surface on one of the adjoining components.
 2. The connecting element as recited in claim 1, wherein formed on the two transitions of the expanded region (4) to the first and the second connecting sleeves (2, 3) is in each case a contact surface (5, 6) which, when the connecting element (1) is mounted, are each in contact with a corresponding surface on both the fuel injector and the fuel line.
 3. The connecting element as recited in claim 2, wherein the geometry of at least one of the two contact surfaces (5, 6) is a section of a spherical surface.
 4. The connecting element as recited in claim 3, wherein the center of the at least one spherical geometry is identical to the point of intersection of the central axis (18) of the connecting element (1) and the central plane of the sealing element (7, 8) which is on the side facing away from the corresponding contact surface (6, 5).
 5. The connecting element as recited in one of claims 2 through 4, wherein a force may be transmitted from the fuel line onto the fuel injector in the axial direction through the two contact surfaces (5, 6) of the connecting element (1).
 6. The connecting element as recited in one of claims 1 through 5, wherein faces (15, 16) of the first and second connecting sleeves (2, 3) have cross-sections of different sizes and the connecting element (1) exerts an axial force in accordance with the fuel pressure and the area ratio.
 7. The connecting element as recited in one of claims 1 through 6, wherein the geometries of the two connecting sleeves (2, 3) are identical. 